Analysis of surgical smoke produced by various energy-based instruments and effect on laparoscopic visibility.

PURPOSE: We analyzed the smoke plume produced by various energy-based laparoscopic instruments and determined its effect on laparoscopic visibility. MATERIALS AND METHODS: The Bipolar Macroforceps, Harmonic Scalpel, Floating Ball, and Monopolar Shears were applied in vitro to porcine psoas muscle. An Aerodynamic Particle Sizer and Electrostatic Classifier provided a size distribution of the plume for particles >500 nm and <500 nm, and a geometric mean particle size was calculated. A Condensation Particle Counter provided the total particle-number concentration. Electron microscopy was used to characterize particle size and shape further. Visibility was calculated using the measured-size distribution data and the Rayleigh and Mie light-scattering theories. RESULTS: The real-time instruments were successful in measuring aerosolized particle size distributions in two size ranges. Electron microscopy revealed smaller, homogeneous, spherical particles and larger, irregular particles consistent with cellular components. The aerosol produced by the Bipolar Macroforceps obscured visibility the least (relative visibility 0.887) among the instruments tested. Particles from the Harmonic Scalpel resulted in a relative visibility of 0.801. Monopolar-based instruments produced plumes responsible for the poorest relative visibility (Floating Ball 0.252; Monopolar Shears 0.026). CONCLUSIONS: Surgical smoke is composed of two distinct particle populations caused by the nucleation of vapors as they cool (the small particles) and the entrainment of tissue secondary to mechanical aspects (the large particles). High concentrations of small particles are most responsible for the deterioration in laparoscopic vision. Bipolar and ultrasonic instruments generate a surgical plume that causes the least deterioration of visibility among the instruments tested.

Pharmacologic manipulation of the porcine ureter: Acute impact of topical drugs on ureteral diameter and peristaltic activity.

BACKGROUND AND PURPOSE: Intraluminal application of pharmacologic agents for acute ureteral dilation may facilitate difficult ureteroscopy. We characterized the in-vivo effects of intraluminal application of verapamil and theophylline on ureteral peristalsis and diameter in a porcine model. MATERIALS AND METHODS: Twenty-four female domestic pigs (35-40 kg) were incorporated into the study. We deployed a giant magneto resistive (GMR) sensor and electromagnetic (EMG) electrodes laparoscopically onto the ureteral surface for simultaneous measurement of the mechanical and electrical signals of ureteral peristalsis, respectively. The ureteral-luminal diameter was measured at three levels by digital retrograde pyelography and standardized to a 10-mm laparoscope. The results were calculated as change in peristalsis and ureteral diameter from baseline during the first hour after drug injection. We tested two smooth-muscle relaxants, verapamil (2 mg/kg) and theophylline (70 mg/kg), with saline and dimethylsulfoxide (DMSO; solvent) as controls. Six pigs were studied for each of the four groups. Hydration, anesthesia, and intra-abdominal pressure were standardized. The serum concentrations of the drugs were measured to determine systemic absorption. RESULTS: During the first 10 minutes after intraluminal drug injection, theophylline caused a significant decrease in ureteral peristalsis (6.75 waves/10 minutes) compared with the control group (1.00/10 minutes; P = 0.02). This trend persisted for the next hour. However, there were no changes from baseline in ureteral width. Ureteral peristalsis and dilation remained similar after the saline and DMSO injections. Verapamil increased the diameter of the proximal ureter compared with the controls throughout the hour after drug injection. Fifteen minutes after the drug injection, the change in the ureteral diameter with verapamil was 1.38 mm (4.14F), while the control group showed a change of 0.27 mm (P = 0.03). At 1 hour, the width of the proximal ureter in the verapamil group had increased by 1.72 mm (5.16F), while the control group had changed by 0.55 mm (P = 0.03). There were no statistically significant changes in the widths of the mid or distal ureter. No ureteral dilation was observed in the other groups. CONCLUSIONS: In the porcine model, intraluminal application of pharmacologic agents produced independent effects on ureteral dilation and peristalsis. Theophylline inhibited ureteral peristalsis, and verapamil produced acute proximal-ureteral dilation. The ability to alter ureteral diameter or peristaltic activity acutely may facilitate ureteroscopy.

Comparison of mechanical and in vivo performance of new and reprocessed harmonic scalpels.

OBJECTIVES: To compare the mechanical and clinical performance of new and reprocessed harmonic scalpels (HS). METHODS: A total of 89 reprocessed and 90 new HS (laparoscopic coagulating shears with a curved blade and 5-mm-diameter shaft) were subjected to visual inspection, destructive testing, and nondestructive mechanical testing. Subsequently, new HS, randomly selected reprocessed HS, and selected reprocessed HS with known abnormalities were graded on clinical performance by 14 surgeons in a porcine model. RESULTS: Visual inspection of the HS discriminated between the new and reprocessed instruments in 11 of the 12 visual criteria (P < or = 0.02). In vitro mechanical testing revealed greater clamp arm dislodge forces for the new HS (P < 0.01) and greater midshaft temperatures for reprocessed HS (P < 0.01). Overall, 65 (73%) of 89 reprocessed and 7 (7.8%) of 90 new HS had gross abnormalities noted on inspection and mechanical evaluation (P < 0.01). The surgeons' evaluation of the instruments during in vivo testing demonstrated that the new instruments manifested significantly greater hemostatic control compared with randomly selected reprocessed HS (P = 0.01) and were significantly better for tissue sticking (P = 0.01), tissue transection (P = 0.02), tissue dissection (P < 0.01), grasping (P < 0.01), and hemostatic control (P = 0.04) compared with reprocessed HS with obvious defects. CONCLUSIONS: In vitro and in vivo data demonstrated significantly greater performance for new HS compared with reprocessed HS. Mechanical testing of reprocessed HS could not adequately distinguish which HS would result in decreased performance. These findings raise important issues of clinical safety in the contemporary quest for cost-effectiveness.

Laparoscopic renal parenchymal hypothermia with novel ice-slush deployment mechanism.

OBJECTIVES: To report the development of a novel, simple-to-use method for laparoscopic deployment of fine-quality saline ice slush by way of a 10-mm end-effector for laparoscopic parenchymal hypothermia. METHODS: A mechanism for making fine ice slush was created, and a 10-mm laparoscopic end-effector was designed and constructed for deployment of the ice slush. The novel ice slush deployment system was tested in a porcine model and compared with that of standard open ice slush cooling. After atraumatic hilar clamping, the cortical and medullary temperatures in the upper, middle, and lower poles were measured with thermocouples. RESULTS: Six pigs were evaluated in each group. In all cases, the kidneys were successfully cooled to our goal temperature of 15 degrees to 25 degrees C within 10 minutes and were maintained at the target temperature for 1 hour. The core body temperature for the slush group was decreased by 3 degrees C but did not change in the open group. The renal temperatures quickly returned to normal on unclamping of the renal hilum. One pig in the open group died of acidosis and another in the same group experienced thrombosis of the renal artery. No complications occurred in the laparoscopic group. CONCLUSIONS: We describe a novel, simple-to-use mechanism for producing and delivering fine ice slush in a laparoscopic setting. The technique achieves optimal parenchymal hypothermia expeditiously.